NUMERICAL SIMULATION OF THREE-DIMENSIONAL SUPERCRITICAL WATER FLOWS IN HYDROTHERMAL SYNTHESIS REACTORS WITH ARBITRARY GEOMETRY

Numerical simulations of mixing flows of supercritical (SC) water and water liquid in a 3-D T-shaped circular pipe and a 3-D cross pipe are conducted using the numerical method developed by our group. The 3-D geometry is generated by Building-Cube Method (BCM) with the stepwise wall treatment. Numerical results of mixing flows in the two pipes are compared and the effect of the inlet temperature is evaluated. In the T-shaped circular reactor, the mixing is periodic and a vortex is observed at the mixing point. The mixing form certainly depends on the SC water temperature. In the counter flow reactor, the SC water flow becomes unsteady and is mixed with water liquid asymmetrically due to the rapid change of thermophysical properties and the buoyancy effect.